Methods, systems, and storage mediums for fiow velocity detection

ABSTRACT

The embodiments of the present disclosure provide a method for a flow velocity detection. The method may include obtaining image data; determining, based on the image data, a parameter of at least one detection point, the parameter being related to a phase change; and determining a first flow velocity of the at least one detection point based on the parameter related to the phase change and a location relationship among the at least one detection point, at least one transmission point, and a plurality of receiving points.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2021/137949, filed on Dec. 14, 2021, the contents of which areincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a field of flow velocity detection, inparticular, relates to systems, methods, and storage mediums for theflow velocity detection.

BACKGROUND

Flow velocity detection may refer to identifying a movement velocity ofa target object based on image data of the target object. The image dataof the target object may be obtained based on phase change of echo dataof the target object at a same position at different time points.However, due to the restriction of scanning modes, only the phase changealong a transmission direction may be detected. In order to obtain anaccurate flow velocity of the target object, it is needed to adjust atransmission angle of a scanning signal or manually adjust position of ascanning probe.

Therefore, it is desirable to provide a method and system for flowvelocity detection, which can automatically detect the flow velocity ofthe target object in any direction and improve the imaging frame rate.

SUMMARY

One aspect of the present disclosure may provide a method for flowvelocity detection. The method may include: obtaining image data;determining, based on the image data, a parameter of at least onedetection point, the parameter being related to a phase change; anddetermining a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.

Another aspect of the present disclosure may provide a system for flowvelocity detection. The system may include: at least one storage mediumstoring a set of instructions; at least one processor in communicationwith the at least one storage medium, when executing the stored set ofinstructions, the at least one processor causes the system to obtainimage data; determine, based on the image data, a parameter of at leastone detection point, the parameter being related to a phase change; anddetermine a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.

Another aspect of the present disclosure may provide a system for flowvelocity detection. The system may include: an image data obtainingmodule configured to obtain image data; a parameter determining moduleconfigured to determine, based on the image data, a parameter of atleast one detection point, the parameter being related to a phasechange; and a first flow velocity determining module configured todetermine a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.

Another aspect of the present disclosure may provide a non-transitorycomputer readable medium including executable instructions, theinstructions, when executed by at least one processor, causing the atleast one processor to effectuate a method comprising: obtaining imagedata; determining, based on the image data, a parameter of at least onedetection point, the parameter being related to a phase change; anddetermining a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.

The embodiments of the present disclosure may group array elements, anddetermine two-dimensional (2D) flow velocity of each detection point byusing a location relationship among transmission points (transmissionfocuses), receiving points (array elements), and/or detection points,and combining with the phase change. Compare with a multi-angletransmission mode, a transmission may obtain phase change of a reflectedsignal under the multi-angle and detect the flow velocity of the targetobject perpendicular to the transmission direction, which may improvesystem utilization of data and the accuracy of system frame rate andspeed evaluation. A full aperture transmission mode may be used toimprove the imaging efficiency, and an unfocused wave mode may be usedto make that the transmission scanning signals point to a same focusposition, which can not only improve a signal to noise ratio, but alsoincrease the frame rate of system, to improve the time resolution of thesystem. Based on the image data and the utilization of the optic flowmethod for calculating the second flow velocity of the at least onedetection point, the flow velocity of the detection point in thethree-dimensional movement field may be converted to the two-dimensionalmovement field for calculation. The first flow velocity and the secondflow velocity may be obtained based on the time resolution (phasechange) and spatial resolution (pixel intensity) of the system,respectively, and thus mutual verification and/or calibration may beachieved. By using a pixel beam synthesis method, using graphicsprocessing unit (GPU) parallel computing based on a mode of groupedarray elements, computing efficiency may be improved and hardware andtime costs may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further illustrated in terms of exemplaryembodiments, and these exemplary embodiments are described in detailwith reference to the drawings. These embodiments are not restrictive.In these embodiments, the same number indicates the same structure,wherein:

FIG. 1 is a schematic diagram illustrating an application scenario of asystem for flow velocity detection according to some embodiments of thepresent disclosure;

FIG. 2 is a block diagram illustrating a processing device for flowvelocity detection according to some embodiments of the presentdisclosure;

FIG. 3 is a flowchart illustrating an exemplary process for determininga first flow velocity of at least one detection point according to someembodiments of the present disclosure;

FIG. 4 a is a schematic diagram illustrating an exemplary divergent waveaccording to some embodiments of the present disclosure;

FIG. 4 b is a schematic diagram illustrating an exemplary plane waveaccording to some embodiments of the present disclosure;

FIG. 5 a is a schematic diagram illustrating an exemplary full aperturetransmission under a divergent wave mode according to some embodimentsof the present disclosure;

FIG. 5 b is a schematic diagram illustrating an exemplary full aperturetransmission under a plane wave mode according to some embodiments ofthe present disclosure;

FIG. 6 is a schematic diagram illustrating exemplary image dataaccording to some embodiments of the present disclosure;

FIG. 7 is a schematic diagram illustrating an exemplary process ofdetermining a first flow velocity of at least one detection point basedon a parameter related to a phase change and a location relationshipamong the at least one detection point, at least one transmission point,and a plurality of receiving points according to some embodiments of thepresent disclosure;

FIG. 8 is a flowchart illustrating an exemplary process of determining asecond flow velocity of at least one detection point according to someembodiments of the present disclosure; and

FIG. 9 is a flowchart illustrating an exemplary process of flow velocitycalibration according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

To more clearly illustrate the technical solutions related to theembodiments of the present disclosure, a brief introduction of thedrawings referred to the description of the embodiments is providedbelow. Obviously, the accompanying drawing in the following descriptionis merely some examples or embodiments of the present disclosure, forthose skilled in the art, the present disclosure may further be appliedin other similar situations according to the drawings without anycreative effort. Unless obviously obtained from the context or thecontext illustrates otherwise, the same numeral in the drawings refersto the same structure or operation.

It should be understood that “system,” “device,” “unit” and/or “module”used in this specification is used for distinguishing differentcomponents, elements, parts or assemblies at different levels. However,if other words can achieve the same purpose, the above-mentioned wordsmay be replaced by other expressions.

As used in the disclosure and the appended claims, the singular forms“a,” “an,” and “the” include plural referents unless the content clearlydictates otherwise. Generally speaking, the terms “comprise” and“include” only imply that the clearly identified steps and elements areincluded, and these steps and elements may not constitute an exclusivelist, and the method or device may further include other steps orelements.

The flowcharts used in the present disclosure illustrate operations thatthe system implements according to the embodiment of the presentdisclosure. It should be understood that a previous operation or asubsequent operation of the flowcharts may not be accurately implementedin order. Instead, a plurality of steps may be processed in reverse orsimultaneously. Moreover, other operations may further be added to theseprocedures, or one or more steps may be removed from these procedures.

FIG. 1 is a schematic diagram illustrating an application scenario of asystem for flow velocity detection according to some embodiments of thepresent disclosure.

A flow velocity detection system 100 may determine a two-dimensionalflow velocity by implementing a method and/or process disclosed in thepresent disclosure.

As shown in FIG. 1 , the flow velocity detection system 100 may include:a scanning device 110, a processing device 120, a terminal device 130, anetwork 140, and/or a storage device 150, etc.

The components of the flow velocity detection system 100 may beconnected in various ways. For example, as shown in FIG. 1 , thescanning device 110 may be connected with the processing device 120 viathe network 140. As another example, the scanning device 110 may bedirectly connected with the processing device 120 (as shown by a dashedtwo-way arrow connecting the scanning device 110 and the processingdevice 120). As a further example, the storage device 150 may bedirectly connected with the processing device 120 or via the network140. As a further example, the storage device 150 may be directly (asshown by the dashed two-way arrow connecting the terminal device 130 andthe processing device 120) and/or via the network 140 connected with theprocessing device 120.

The scanning device 110 may obtain scanning data by scanning a targetobject. In some embodiments, the scanning device 110 may transmit asignal (e.g., an ultrasonic wave) to the target object or a portionthereof and receive a reflected signal (e.g., a reflected ultrasonicwave) from the target object or a portion thereof. In some embodiments,the scanning device 110 may include a scanner. The scanning device maybe used to transmit a signal and/or receive a signal. The scanningdevice may include but is not limited to an ultrasound probe, a radarprobe, etc.

The processing device 120 may process data and/or information obtainedfrom the scanning device 110, the terminal device 130, and/or thestorage device 150. For example, the processing device 120 may determinea first flow velocity of at least one detection point based on the imagedata. As a further example, the processing device 120 may determine atarget flow velocity of the at least one detection point based on thefirst flow velocity and the second flow velocity of the at least onedetection point. In some embodiments, the processing device 120 mayinclude a central processing unit (CPU), a digital signal processor(DSP), a system on a chip (SoC), a microcontroller unit (MCU), etc.,and/or any combination thereof. In some embodiments, the processingdevice 120 may include a computer, a user console, a single server orgroup of servers, or the like. The server group may be centralized ordistributed. In some embodiments, the processing device 120 may be localor remote. For example, the processing device 120 may access informationand/or data stored in the scanning device 110, the terminal device 130,and/or the storage device 150 via the network 140. As another example,the processing device 120 may be directly connected with the scanningdevice 110, the terminal device 130, and/or the storage device 150 toaccess stored information and/or data. In some embodiments, theprocessing device 120 may be implemented on a cloud platform. By way ofexample only, the cloud platform may include a private cloud, a publiccloud, a hybrid cloud, a community cloud, a distributed cloud, aninter-cloud, a multi-cloud, etc., or any combination thereof. In someembodiments, the processing device 120 or a portion of the processingdevice 120 may be integrated into the scanning device 110.

The terminal device 130 may receive instruction (e.g., an ultrasonicexamination mode), and/or display a flow velocity detection resultand/or an image to a user. The terminal device 130 may include a mobiledevice 131, a tablet computer 132, a notebook computer 133, etc., or anycombination thereof. In some embodiments, the terminal device 130 may bepart of the processing device 120.

The network 140 may include any suitable network that facilitatesexchange of information and/or data for the flow velocity detectionsystem 100. In some embodiments, one or more components of flowdetection system 100 (e.g., the scanning device 110, the processingdevice 120, the storage device 150, the terminal device 130) maycommunicate information and/or via network 140 with the one or moreother components of flow detection system 100. For example, theprocessing device 120 may receive user instructions from the terminaldevice via the network. As another example, the scanning device 110 mayobtain an ultrasound transmission parameter from processing device 120via the network 140. The network 140 may include a public network (e.g.,the Internet), a private network (e.g., a local area network (LAN), awide area network (WAN)), a wired network (e.g., an Ethernet network), awireless network (e.g., an 802.11 network, a Wi-Fi network), a cellularnetwork (e.g., a long term evolution (LTE) network), a frame relaynetwork, a virtual private network (VPN), a satellite network, atelephone network, a router server computer, and/or any combinationthereof. For example, the network 140 may include a cable network, awired network, an optical fiber network, a telecommunications network,an intranet, a wireless local area network (WLAN), a metropolitan areanetwork (MAN), a public switched telephone network (PSTN), a Bluetooth™network, a ZigBee™ network, a near field communication (NFC) network, orany combination thereof. In some embodiments, the network 140 mayinclude one or more network access points. For example, the network 140may include a wired and/or wireless network access point such as a basestation and/or an internet switching point, the one or more componentsof flow velocity detection system 100 may be connected with the network140 through the access points to exchange data and/or information.

The storage device 150 may store data, instruction, and/or any otherinformation. In some embodiments, the storage device 150 may store dataobtained from the scanning device 110, the terminal device 130, and/orthe processing device 120. In some embodiments, the storage device 150may store data and/or instruction, the processing device 120 execute oruse the data and instruction to perform the exemplary method/systemdescribed in the present disclosure. In some embodiments, the storagedevice 150 may include a mass storage, a removable memory, a volatileread-write memory, a read-only memory (ROM), etc., or any combinationthereof. The exemplary mass storage may include a magnetic disk, anoptical disk, a solid-state disk, or the like. The exemplary removablememory may include a flash drive, a floppy disk, an optical disk, amemory card, a compressed disk, a magnetic tape, or the like. Theexemplary volatile read/write memory may include a random access memory(RAM). The exemplary RAM may include a dynamic random access memory(DRAM), a double data rate synchronous dynamic random access memory (DDRSDRAM), a static random access memory (SRAM), a thyristor random accessmemory (T-RAM), a zero capacitance random access memory (Z-RAM), or thelike. The exemplary ROM may include a mask read only memory (MROM), aprogrammable read only memory (PROM), an erasable programmable read onlymemory (EPROM), an electrically erasable programmable read only memory(EEPROM), an optical disk read only memory (CD-ROM), and a digitalversatile disk read only memory. In some embodiments, the storage device150 may be executed on a cloud platform. For example, the cloud platformmay include a private cloud, a public cloud, a hybrid cloud, a communitycloud, a distributed cloud, an internal cloud, a multi-layer cloud, orany combination thereof.

In some embodiments, the storage device 150 may communicate the one ormore components of flow velocity detection system 100 (e.g., thescanning device 110, the processing device 120, the terminal device 130)by connecting with the network 140. The one or more components of flowvelocity detection system 100 may access data or instructions stored inthe storage device 150 via the network 140. In some embodiments, thestorage device 150 may be directly connected or communicate with the oneor more other components of the flow velocity detection system 100(e.g., the scanning device 110, the processing device 120, the storagedevice 150, the terminal device 130). In some embodiments, the storagedevice 150 may be part of the processing device 120.

FIG. 2 is a block diagram illustrating a processing device for flowvelocity detection according to some embodiments of the presentdisclosure.

In some embodiments, the processing device 120 may include an image dataobtaining module 210, a parameter determination module 220, and/or afirst flow velocity determination module 230, a second flow velocitydetermination module 240 and/or a flow velocity calibration module 250.

The image data obtaining module 210 may be configured to obtain an imagedata. In some embodiments, the image data may include data obtained byscanning under a mode B.

In some embodiments, the image data obtaining module 210 may obtain theimage data by utilizing full aperture transmission. In some embodiments,the full aperture transmission may include a full aperture transmissionunder an unfocused wave transmission mode.

In some embodiments, the image data obtaining module 210 may group arrayelements of a scanning probe to obtain a plurality of groups of arrayelements. Each group of array elements in the plurality of groups ofarray elements may include one or more array elements. In someembodiments, the scanning probe may include any one of a linear arrayprobe, a convex array probe, and/or a phased array probe. In someembodiments, the image data may include a plurality of image data. Insome embodiments, each group of image data in the plurality of groups ofimage data may correspond to a group of array elements in the pluralityof groups of array elements. In some embodiments, a group of image datamay be obtained by demodulation and/or beam synthesis based on thereflected signal received by the corresponding group of array elements.

The parameter determination module 220 may be configured to determine,based on the image data, a parameter of at least one detection point.The parameter may be related to a phase change. In some embodiments, theparameter related to a phase change may include a phase change rate. Insome embodiments, the parameter determination module 220 may beconfigured to execute one or more of the following: determining at leasttwo image data segments that are adjacent with respect to time receivedby each array element in the image data; determining a phase change rateof at least one detection point corresponding to each group of arrayelements based on the at least two image data segments that are adjacentwith respect to time.

The first flow velocity determination module 230 may be configured todetermine a first flow velocity of one or more detection points. In someembodiments, the first flow velocity determination module 230 maydetermine at least one first flow velocity of the at least one detectionpoint based on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points. In someembodiments, the first flow velocity determination module 230 maydetermine the first flow velocity of the at least one detection point byGPU parallel computing.

In some embodiments, the first flow velocity determination module 230may determine the first flow velocity of the at least one detectionpoint by calculating a characteristic matrix for the plurality of arrayelements, respectively, and integrating the calculation results of theplurality of array elements based on the parameter related to the phasechange and the location relationship among the at least one detectionpoint, the at least one transmission point, and the plurality ofreceiving points.

In some embodiments, the first flow velocity determination module 230may be configured to execute one or more of the following: determining aresultant spatial displacement vector corresponding to each group ofarray elements based on the location relationship among the at least onedetection point, the at least one transmission point, and the pluralityof receiving points; determining a first characteristic matrixcorresponding to each group of array elements based on the resultantspatial displacement vector; and determining a first flow velocity ofthe at least one detection point based on the phase change rate of theat least one detection point corresponding to each group of arrayelements and the first characteristic matrix corresponding to each groupof array elements.

In some embodiments, the first flow velocity determination module 230may be configured to execute one or more of following: determining afirst auxiliary calculation matrix corresponding to each group of arrayelements based on the phase change rate of the at least one detectionpoint corresponding to each group of array elements and the resultantspatial displacement vector corresponding to each group of arrayelements; determining a second auxiliary calculation matrixcorresponding to each group of array elements based on the firstauxiliary calculation matrix corresponding to each group of arrayelements; obtaining a third auxiliary calculation matrix by accumulatingthe first auxiliary calculation matrix corresponding to each group ofarray elements; obtaining a fourth auxiliary calculation matrix byaccumulating the second first auxiliary calculation matrix correspondingto each group of array elements; and determining the first flow velocityof the at least one detection point based on the third auxiliarycalculation matrix and the fourth auxiliary calculation matrix.

In some embodiments, the first flow velocity determination module 230may be configured to execute one or more of the following: determining aspatial displacement vector corresponding to each receiving point basedon the location relationship among the at least one detection point, theat least one transmission point, and the plurality of receiving points;and determining the resultant spatial displacement vector correspondingto each group of array elements based on the spatial displacement vectorcorresponding to each receiving point and a weight corresponding to eachreceiving point. In some embodiments, the first flow velocitydetermination module 230 may obtain the resultant spatial displacementvector corresponding to each group of array elements by utilizing theweight of each receiving point in each array element and a weighted sumof the spatial displacement vector of each receiving point in each arrayelement. In some embodiments, the weight corresponding to each receivingpoint may be determined based on a distance between each receiving pointand at least one detection point.

The second flow velocity determination module may be configured todetermine a second flow velocity of one or more detection points. Insome embodiments, the second flow velocity determination module 240 maydetermine a time intensity gradient and/or a spatial intensity gradientof the at least one detection point based on the image data; and/ordetermine the second flow velocity of the at least one detection pointbased on the time intensity gradient and/or spatial intensity gradientof the at least one detection point.

The flow velocity calibration module 250 may be configured to obtain atarget flow velocity by calibrating a flow velocity of one or moredetection points. In some embodiments, the flow velocity calibrationmodule 250 may obtain a target flow velocity of the at least onedetection point by performing the velocity calibration based on thefirst flow velocity and/or the second flow velocity of the at least onedetection point. In some embodiments, the flow velocity calibrationmodule 250 may be configured to execute one or more of the following:determining a difference between the first flow velocity and the secondflow of the at least one detection point; in response to that thedifference is not greater than a threshold, determining the target flowvelocity of the at least one detection point based on the first flowvelocity and the second flow velocity of the at least one detectionpoint; and in response to that the difference is greater than thethreshold, determining a target flow velocity of at least one adjacentdetection point adjacent to the at least one detection point, andinterpolating the target flow velocity of the at least one adjacentdetection point to obtain the target flow velocity of the at least onedetection point.

FIG. 3 is a flowchart illustrating an exemplary process for determininga first flow velocity of at least one detection point according to someembodiments of the present disclosure.

In some embodiments, the process 300 may be executed by the scanningdevice 110 and/or the processing device 120. In some embodiments, theprocess 300 may be stored in a storage device, such as the storagedevice 150, when the flow velocity detection system 100 (e.g., theprocessing device 120) executes the program or instruction, the process300 may be implemented. In some embodiments, the process 300 may beperformed by one or more modules in FIG. 2 . As shown in FIG. 3 , theprocess 300 may include:

In 310, the image data (e.g., the image data of the target object) maybe obtained. In some embodiments, the operation 310 may be performed bythe image data obtaining module 210.

The image may be a carrier of visual information describing the targetobject. The image data may include data used to generate an image. Insome embodiments, the image data obtaining module 210 may obtain theimage data based on the scanning probe. Specifically, the scanning probemay transmit a scanning signal to the target object or any one part ofthe target object, receive one or more reflected signals from the targetobject or any one part of the target object, and further obtain theimage data based on the one or more reflected signals.

In some embodiments, the target object may include a human body, anorgan, a damaged part, a tumor, a body, an object, etc. For example, thetarget object may be one or more diseased tissues of the heart, theimage may be a medical image of the one or more diseased tissues of theheart. As another example, the target object may be an obstacle during aflight of an aircraft, and the image may be a flight radar chart. As afurther example, the target object may be a fluid, and the image may bea flow pattern diagram.

In some embodiments, the image format may include, but is not limitedto, a Joint Photographic Experts Group (JPEG) image format, a taggedimage file format (TIFF) image format, a Graphics Interchange Format(GIF) image format, a Kodak flash pix (FPX) image format, a digitalimaging and communications in medicine (DICOM) image format, or thelike.

In some embodiments, the image format may include, but is not limitedto, an ultrasonic wave image and/or an electromagnetic wave image, etc.Corresponding to the type of image, the scanning probe may include butis not limited to, an ultrasonic wave probe or a radar probe, or one ormore combinations thereof. In some embodiments, the scanning signal mayinclude but is not limited to, an ultrasonic wave or an electromagneticwave, or one or more combinations thereof. In some embodiments, thereflected signal may include but is not limited to, an ultrasonic wavereflected signal or an electromagnetic wave reflected signal, or one ormore combinations thereof.

In some embodiments, the image data corresponding to the electromagneticwave image may be data obtained by scanning under a mode B. In someembodiments, the image data corresponding to the electromagnetic waveimage may be a two-dimensional ultrasonic wave image in which anamplitude of an ultrasonic wave reflection signal corresponding to asingle ultrasonic transmission is expressed by brightness.

In some embodiments, the scanning probe may include an array element.The array element may be an assembly on the scanning probe configured totransmit the scanning signal(s) and/or receive the reflected signal(s).

In some embodiments, according to the arrangement of array elements onthe scanning probe, the scanning probe may include a linear array probe,a convex array probe, or a phased array probe, or one or morecombinations thereof. The array elements of the linear array probe, theconvex array probe, and/or the phased array probe may be arranged into astraight line segment (as shown in FIG. 4 a ), an arc segment (as shownin FIG. 4 b ), and/or a square matrix (not shown), respectively.

In some embodiments, the array element of the scanning probe may includepiezoelectric material, for example, the array element of the ultrasonicprobe and/or the radar probe may be barium titanate, lead titanate, leadzirconate titanate, or the like.

In some embodiments, the scanning probe may include array elements withmultiple frequencies and control circuits corresponding to each arrayelement, and the scanning probe may generate different scanning signalswith different frequencies by exciting the array elements at differentpositions using a pulse signal.

For example, an ultrasonic scanning probe may transmit the signal to thetarget object or a portion thereof by converting an electric signalpulse into an ultrasonic signal through the array element, and/orconverting the reflected ultrasonic signal of the target object or aportion thereof into an electric signal (i.e., image data).

In some embodiments, each control circuit may excite an array element.Specifically, the scanning probe may transmit each pulse signal to thecorresponding control circuit, and each control circuit excites acorresponding array element based on the pulse signal, and thus scanningsignals with different or the same frequencies may be emitted atdifferent time points or at the same time.

In some embodiments, the image data obtaining module 210 may obtain theimage data by utilizing full array element (also referred to as fullaperture) transmission.

The full aperture transmission may be a transmission mode fortransmitting the scanning signal by utilizing all array elements of thescanning probe. It should be understood that the image data obtainingmodule 210 may obtain an image frame corresponding to all detectionregions (i.e., the target object or a portion thereof) based on a signalfull aperture transmission. In some embodiments, the image dataobtaining module 210 may obtain an image sequence (or video)corresponding to the detection region (i.e., the target object or aportion thereof).

In some embodiments, the full aperture transmission may include a fullaperture transmission under an unfocused wave transmission mode (e.g., adivergent wave transmission mode and/or a plane wave transmission mode).

The divergent wave transmission mode may be a transmission mode in whicha focus is above the scanning probe during the transmission. As shown inFIG. 4 a , a focus A may be above the scanning probe when transmittingthe divergent wave, and all the array elements a-b above the scanningprobe may transmit the scanning signal(s). The plane wave transmissionmode may be a transmission mode with the focus at infinity during thetransmission. As shown in FIG. 4 b , the focus may be at infinity whentransmitting the plane wave, and all the array elements above thescanning probe c-d may transmit the scanning signal.

In some embodiments, the image data obtaining module 210 may divide theplurality of full aperture transmission into a plurality of transmissiongroups under the divergent wave transmission mode, and each transmissiongroup may include at least two adjacent full aperture transmissions. Insome embodiments, a focus position corresponding to the full aperturetransmission in each transmission group may be the same.

For example, the image data obtaining module 210 may divide the 40 fullaperture transmissions into 20 transmission groups under the divergentwave mode, and each transmission group may include two adjacent fullaperture transmissions; the first transmission group may include a firstfull aperture transmission and a second full aperture transmission, andfocus positions corresponding to the first full aperture transmissionand the second full aperture transmission may be both the position ofthe first focus; the second transmission group may include a third fullaperture transmission and a fourth full aperture transmission, and focuspositions corresponding to the third full aperture transmission and thefourth full aperture transmission may be both the position of the secondfocus; . . . ; and the 20^(th) transmission group may include a 39^(th)full aperture transmission and a 40^(th) full aperture transmission, andfocus positions corresponding to the 39^(th) full aperture transmissionand the 40^(th) full aperture transmission may be both the position ofthe 20^(th) focus.

In some embodiments, the image data obtaining module 210 may obtain theplurality of array elements by grouping the array elements of thescanning probe, wherein each group of array elements of the plurality ofarray elements may include one or more array elements.

In some embodiments, each group of array elements may include the samecount of array elements. For example, as shown in FIG. 5 a , the imagedata obtaining module 210 may divide the 128 array elements of thescanning probe into 16 groups of array elements, and each group of arrayelements may include 8 array elements.

In some embodiments, the counts of array elements included in any twogroups of array elements may be different. For example, the image dataobtaining module 210 may reduce the count of array elements in the arrayelement group corresponding to a region of non-interest, and increasethe count of array elements in the array element group corresponding toa region of interest. For example, a center position of the detectionregion may be the region of interest, and two sides of the detectionregion may be the region of non-interest, then the image data obtainingmodule 210 may divide the 128 array elements of the scanning probe into8 groups of array elements, and the count of array elements in the 9groups of array elements may be 8, 8, 8, 8, 16, 16, 16, 16, 8, 8, 8, 8,respectively.

In some embodiments, the image data may include a plurality of imagedata. Each group of image data in the plurality of image data maycorrespond to a group of array elements in the plurality of arrayelements.

In some embodiments, the array element group corresponding to each groupof image data may be an array element group receiving the reflectedsignal corresponding to the group of image data. As shown in FIG. 5 a ,based on the scanning signal transmitted by a third group of arrayelements, a first group of array elements may receive the correspondingreflected signal. The image data obtaining module 210 may generate agroup of image data (e.g., the first group of image data) based on thereflected signal received by the first group of array elements, thefirst group of array elements may be the array group corresponding tothe group of image data. Similarly, a second group of array elements, athird group of array elements, . . . , and a 16^(th) group of arrayelements may correspond to a second group of image data, a third groupof image data, . . . , and a 16^(th) group of image data, respectively.

In some embodiments, each group of image data corresponding to eachgroup of array elements may correspond to an image region (e.g., a partof image). As shown in FIG. 5 a , the image data obtaining module 210may generate a first image region (e.g., an image of the detectionregion within a CK range and a CE range) based on the first group ofimage data. Similarly, the image data obtaining module 210 may generatea second image region, a third image region, . . . , and a 16^(th) imageregion based on the second group of image data, the third group of imagedata, . . . , and the 16^(th) group of image data, respectively. In someembodiments, the first image region, the second image region, the thirdimage region, . . . , and the 16^(th) image region may be different fromeach other to form the detection region. It should be understood thatthe image data obtaining module 210 may spatially divide the image datacorresponding to the detection region into the plurality of groups ofimage data corresponding to the plurality of image regions based on thearray element grouping.

In some embodiments, each group of image data may be obtained byperforming demodulation and/or beam synthesis on the reflected signalsreceived by a corresponding group of array elements.

The demodulation may be a process of restoring a digital band signal toa digital baseband signal.

The beam synthesis may be a process of weighted synthesis of multiplereflected signals. In some embodiments, the image data obtaining module210 may perform the weighted synthesis on the reflected signals receivedby two or more array elements in each array element group, and furtherdetermine the image data group corresponding to the plurality ofreflected signals received by the array element group.

For example, the image data obtaining module 210 may generate the firstgroup of image data, the second group of image data, . . . , and the16^(th) group of image data based on the reflected signals received bythe first group of array elements, the second group of array elements, .. . , and the 16^(th) group of array elements, respectively.

In 320, a parameter of at least one detection point may be determinedbased on the image data. The parameter may be related to a phase change.In some embodiments, the operation 310 may be performed by the parameterdetermination module 220.

The detection point may be a space point on the detection region (i.e.,the target object or a portion thereof). As shown in FIG. 5 a , thedetection point may be a space point D on the detection region.

The parameter related to the phase change may be a parameterrepresenting a time-varying phase of the reflected signals returningfrom the detection point. In some embodiments, the parameter related tothe phase change may include a phase change rate.

The phase change rate may be a phase change of the reflected signalsreturned from the detection point per unit time. It should be understoodthat the reflected signals may be affected by the direction of thescanning signals and/or a motion of the detection point. Therefore, inorder to obtain a moving speed of the detection point based on the phasechange rate, the phase change rate may be a phase change of thereflected signals corresponding to the scanning signals in a samedirection per unit time. In some embodiments, the direction of thescanning signals may be determined based on the position of thetransmission point. In some embodiments, the same scanning signals maycorrespond to the same focus.

For example, the phase change rate of the focus under the plane wavemode at infinity may be a phase change of the reflected signalscorresponding to scanning signals obtained by any two adjacenttransmissions per unit time.

As another example, the phase change rate under the divergent wave modemay be a phase change of the reflected signals corresponding to scanningsignals obtained by any two adjacent transmissions in a sametransmission group per unit time. For example, the phase change rate maybe a phase change of the reflected signals corresponding to the firstfull aperture transmission and the second full aperture transmission inthe first transmission group per unit time, wherein the focus positionsof the first full aperture transmission and the second full aperturetransmission may both be position of a point C.

In some embodiments, the parameter determination module 220 maydetermine, in the image data, at least two image data segments that areadjacent with respect to the time received by each group of arrayelements.

The image data segment may be a part of image data corresponding to eachimage frame.

In some embodiments, the processing device may generate an image framebased on the image data corresponding to a scanning signal transmittedby the scanning probe, and generate an image based on the plurality ofimage frames. For example, under the full aperture transmission mode ofthe scanning probe, each image frame may be obtained based on the imagedata corresponding to a scanning signal, and each image may be obtainedbased on 40 image frames. For example, under the full aperturetransmission mode, a first image frame, a second image frame, . . . ,and a 40^(th) image frame may be generated based on a first scanningsignal, a second scanning signal, . . . , and a 40^(th) scanning signal,respectively. Further, based on a transmission sequence of the scanningsignal corresponding to each image frame, the image may be obtained bycompositing the first image frame, the second image frame, . . . , andthe 40^(th) image frame.

As set forth above, each group of image data corresponding to each groupof array elements may correspond to an image region, further, based onthe plurality of image regions corresponding to the plurality of arrayelements, the parameter determination module 220 may divide the imagedata corresponding to each image frame into a plurality of image datasegments. As shown in FIG. 6 , the image data corresponding to the firstimage frame may be divided into a corresponding image data segment 1-1(i.e., a first image data segments of the first frame image), an imagedata segment 1-2 (i.e., a second image data segment of the first frameimage), . . . , and an image data segment 1-16 (i.e., a 16^(th) imagedata segment of the first frame image) based on the first image region,the second image region, . . . , and the 16^(th) image region; the imagedata corresponding to the 40^(th) image frame may be divided into acorresponding image data segment 40-1 (i.e., a first image segment ofthe 40^(th) frame image), an image data segment 40-2 (i.e., a secondimage segment of the 40^(th) frame image), . . . , and an image datasegment 40-16 (i.e., a 16^(th) image segment of the 40^(th) frame image)based on the first image region, the second image region, . . . , andthe 16^(th) image region.

It should be understood that each image data segment may spatiallycorrespond to a part of the image data corresponding to each image frameand correspond to a part of each group of image data with respect to thetime.

In some embodiments, the plurality of image frames may be obtained bycompositing the plurality of image data segments based on a spatialrelationship firstly, and the image data of the detection region may beobtained based on a time relationship. As shown in FIG. 6 , the imagedata of the detection region corresponding to the first frame may beobtained based on the image data of 16 image regions corresponding tothe first image frame. Similarly, the image data of the whole detectionregion corresponding to the 40^(th) image frame may be obtained based onthe image data of the 16 image regions corresponding to the first imageframe. Further, the image data of the whole detection region may beobtained based on the 40 image frames (each image frame may correspondto the image data of the whole detection region).

In some embodiments, a plurality of image data may be obtained bycompositing the plurality of image data segments based on a timerelationship firstly, and the image data of the detection region may beobtained based on the spatial relationship. As shown in FIG. 6 , thefirst group of image data corresponding to the first image region may beobtained based on the first image data segment of each image frame inthe 40 image frames corresponding to the first image region. Similarity,the 16^(th) group of image data corresponding to the 16^(th) image datamay be obtained based on the 16^(th) image data segment of each imageframe in the 40 image frames corresponding to the 16^(th) image region.Further, the image data of the whole detection region may be obtainedbased on the 16 groups of image data of the 16 image regions.

In some embodiments, the at least two image data segments that areadjacent with respect to the time received by each group of arrayelements may be at least two image data segments of scanning signalsthat are obtained by adjacent transmissions at the same focus positionand received by each group of array elements. For example, at least twoimage data segments that are adjacent with respect to time andcorrespond to the same focus position, which are received by each groupof array elements may be two consecutive image data segmentscorresponding to the scanning signals in the same transmission groupunder the divergent wave transmission mode, such as a first image datasegment I₁ ² and a second image data segment I₁ ² received by the firstgroup of array elements when the transmission focus is at the point C.As another example, the at least two image data segments that areadjacent with respect to the time received by each group of arrayelements may be consecutive multiple image data segments under the planewave transmission mode, such as the second image data segment I₁ ² athird image data segment I₁ ³, and a fourth image data segment I₁ ⁴received by the first group of array elements.

In some embodiments, the parameter determination module 220 maydetermine the phase change rate of the at least one detection pointcorresponding to each group of array elements based on the at least twoimage data segments that are adjacent with respect to the time.

As set forth above, each group of image data may correspond to a part ofimage of the detection region (i.e., an image region), each image datasegment may include the image data of the at least one detection point.As shown in FIG. 5 a , the image data segment (or image data group)corresponding to the first group of array elements may include the imagedata of the detection point within a CK range and a CE range.

In some embodiments, the parameter determination module 220 maydetermine a phase change rate of the at least one detection point ofeach group of array elements based on the at least two image datasegments that are adjacent with respect to the time by Equation (1):

$\begin{matrix}{{{\overset{.}{\phi}}_{k} \approx \frac{\arg I_{k}^{i + 1}I_{k}^{i}}{t_{k}^{i + 1} - t_{k}^{i}}},} & (1)\end{matrix}$

Wherein {dot over (ϕ)}_(k) represents a phase change rate of the atleast one detection point received by the K^(th) group of arrayelements; I_(k) ^(i+1) and I_(k) ^(i) represent (i+1)^(th) and i^(th)image data segments received by the K^(th) group of array elements basedon the scanning signal corresponding to the same focus; t_(k) ^(i+1) andt_(k) ^(i) represent transmission time of the scanning signalscorresponding to the (i+1)^(th) and i^(th) image data segments receivedby the K^(th) group of array elements.

For example, the second frame and the first image data segment receivedby the first group of array elements based on the scanning signalcorresponding to the same focus C may be I₁ ² and I₁ ¹, respectively,during a transmission time interval of the scanning signal correspondingto the second frame and the first image data segment received by thefirst group of array elements, the phase change rate of the at least onedetection point received by the first group of array elements may be{dot over (ϕ)}₁.

Similarly, the parameter determination module 220 may determine theplurality of phase change rates of the at least one detection point ofeach group of array elements based on the plurality of image datasegments that are adjacent with respect to the time. Specifically, theparameter determination module 220 may obtain the correspondingplurality of phase change rates based on any two adjacent image datasegments in the plurality of image data segments that are adjacent withrespect to the time according to Equation (1), and further, obtain afinal phase change rate based on the plurality of phase change rates. Insome embodiments, the parameter determination module 220 may obtain afinal phase change rate by calculating an average, a weighted average,or a variance, of the plurality of phase change rates.

For example, for the second image data segment I₁ ², the third imagedata segment I₁ ³, and the fourth image data segment I₁ ⁴ received bythe first group of array elements based on the scanning signals of thesame transmission focus, the parameter determination module 220 mayobtain a phase change rate {dot over (ϕ)}₁ ^(2,3) based on the secondimage data segment I₁ ² and the third image data segment I₁ ³, obtain aphase change rate {dot over (ϕ)}₁ ^(3,4) based on the third image datasegment I₁ ³ and the fourth image data segment I₁ ⁴, calculate anaverage of the phase change rate {dot over (ϕ)}₁ ^(2,3) and the phasechange rate {dot over (ϕ)}₁ ^(3,4), and obtain the phase change rate{dot over (ϕ)}₁ of the at least one detection point of the first groupof array elements.

In 330, a first flow velocity of the at least one detection point may bedetermined based on the parameter related to the phase change and thelocation relationship among the at least one detection point, the atleast one transmission point, and the plurality of receiving points.

In some embodiments, the operation 330 may be performed by the firstflow velocity determination module 230.

The transmission point may be any array element in the array elementgroup that transmits the scanning signal to the detection point. Asshown in FIG. 5 a , a second array element in the third group of arrayelements that transmits the scanning signal to a detection point D maybe a transmission point 3-2 corresponding to the detection point D.

The receiving point may be any array element in the array element groupthat receives the reflected signals from the detection point. As shownin FIG. 5 a , the fifth array element in the first group of arrayelements that receives the scanning signal from the detection point Dmay be a receiving point 1-5 corresponding to the detection point D.

The first flow velocity may be the flow velocity of the detection pointdetermined based on the phase change of the reflected signals.

In some embodiments, the first flow velocity determination module 230may obtain the first flow velocity of the at least one detection pointby calculating a characteristic matrix for the plurality of groups ofarray elements, respectively, and integrating the calculation results ofthe plurality of groups of array elements based on the parameter relatedto the phase change and the location relationship among the at least onedetection point, the at least one transmission point, and the pluralityof receiving points.

More descriptions about the process of obtaining the first flow velocitymay be referred to FIG. 7 and the related descriptions, which may not berepeated here.

FIG. 7 is a schematic diagram illustrating an exemplary process ofdetermining a first flow velocity of at least one detection point basedon a parameter related to phase change and a location relationship amongthe at least one detection point, at least one transmission point, and aplurality of receiving points according to some embodiments of thepresent disclosure. In some embodiments, the process 700 may beperformed by the scanning device 110 and/or the processing device 120.For example, the process 700 may be implemented as a set of instructions(e.g., an application) stored in a storage device (e.g., the storagedevice 150). In some embodiments, the flow velocity detection system 100(e.g., the processing device 120) may execute the set of instructionsand may accordingly be directed to perform the process 700. In someembodiments, the process 700 may be accomplished with one or moreadditional operations not described and/or without one or more of theoperations discussed. Additionally, the order of the operations ofprocess 700 illustrated in FIG. 7 and described below is not intended tobe limiting.

In 710, a resultant spatial displacement vector corresponding to eachgroup of the array elements may be determined based on the locationrelationship among the at least one detection point, the at least onetransmission point, and the plurality of receiving points.

In some embodiments, each transmission point may transmit a scanningsignal to the at least one detection point. Specifically, eachtransmission point may transmit the scanning signal(s) to the detectionpoint in a corresponding transmission direction in the detection region.

In some embodiments, the transmission direction of each transmissionpoint may be determined based on the corresponding focus position whenthe transmission point transmits the scanning signal. For example, thetransmission direction may be directed from the focus position to theposition of the transmission point. As shown in FIG. 5 a , atransmission direction of a transmission point 3-2 (i.e., a second arrayelement of the third group of array elements) may be directed from thetransmission point C to the detection point D (i.e., a {right arrow over(CD)} direction), the transmission point 302 may transmit the scanningsignal to a detection point (i.e., a detection point on line segment FG)on the {right arrow over (CD)} direction in the detection region underthe divergent wave mode. As shown in FIG. 5 b , the transmissiondirection of the transmission point under the plane wave mode may be avertical direction.

In some embodiments, each receiving point may receive a reflected signalobtained based on the scanning signal of the at least one detectionpoint from the at least one detection point. Specifically, eachreceiving point may receive the reflected signal from the detectionpoint in a corresponding receiving direction in the detection region. Insome embodiments, the receiving direction of each receiving point may bedetermined based on positions of the receiving point and detectionpoint. For example, the receiving direction may be directed from theposition of the receiving point to the position of the detection point.As shown in FIG. 5 a , a receiving direction of a receiving point 1-5(i.e., a fifth array element of the first group of array elements) maybe directed from position J of the receiving point 1-5 to the detectionpoint D (i.e., a {right arrow over (JD)} direction), and the receivingpoint 1-5 may receive the reflected signal from the detection point onthe {right arrow over (JD)} direction in the detection region.

A resultant spatial displacement vector corresponding to each group ofthe array elements may be a unit flow velocity of the at least onedetection point detected by each group of array elements, which mayrepresent a flow velocity direction of the at least one detection pointdetected by each group of array elements. In some embodiments, theresultant spatial displacement vector corresponding to each group of thearray elements may be a resultant vector of the spatial displacementvectors corresponding to all the array elements (i.e., the receivingpoint) in each group of array elements.

In some embodiments, the first flow velocity determination module 230may determine the spatial displacement vector corresponding to eachreceiving point based on the location relationship among the at leastone detection point, the at least one transmission point, and/or theplurality of receiving points.

The spatial displacement vector of a detection point corresponding tothe receiving point may be a resultant vector of unit vectors of thedetection point in the receiving direction and unit vectors of thedetection point in the transmission direction. As shown in FIG. 5 a , aspatial displacement vector of the detection point D corresponding tothe receiving point 1-5 may be a unit vector of the detection point D inthe receiving direction {right arrow over (JD)} and a resultant vector{right arrow over (p)} of the unit vector in the transmission direction{right arrow over (CD)}.

In some embodiments, the first flow velocity determination module 230may determine a spatial displacement vector of a detection pointcorresponding to each receiving point based on Equation (2):

$\begin{matrix}{{p_{k}^{m} = {{{\nabla{❘{x - x^{T}}❘}} + {\nabla{❘{x - x_{k,m}^{R}}❘}}} = {\frac{x - x^{T}}{❘{x - x^{T}}❘} + \frac{x - x_{k,m}^{R}}{❘{x - x_{k,m}^{R}}❘}}}},} & (2)\end{matrix}$

Wherein p_(k) ^(m) represents a spatial displacement vector of adetection point corresponding to an m^(th) array element (i.e., anm^(th) receiving point) in the k^(th) group of receiving array elements;x represents the position of the detection point; x^(T) representsposition of the transmission point; and x_(k,m) ^(R) represents theposition of the m^(th) array element in the k^(th) group of receivingarray elements.

Further, in some embodiments, the first flow velocity determinationmodule 230 may determine the resultant spatial displacement vectorcorresponding to each group of array group based on the spatialdisplacement vector corresponding to each receiving point and the weightcorresponding to each receiving point.

The weight corresponding to each receiving point may representimportance of each receiving point to the at least one detection point.In some embodiments, for the different detection points, the weight ofeach receiving point may be different.

In some embodiments, the weight of each receiving point may bedetermined based on a distance between each receiving point and the atleast one detection point.

In some embodiments, the weight of each receiving point may bepositively correlated with the distance between each receiving point andthe at least one detection point. For example, the closer the receivingpoint is to a certain detection point, the smaller the weight of thereceiving point relative to the detection point. As shown in FIG. 5 a ,the closer a receiving point 1-1, a receiving point 1-5, . . . , or areceiving point 2-5 to the detection point, the smaller the weight ofthe receiving point 1-1, the receiving point 1-5, . . . , or thereceiving point 2-5.

In some embodiments, the first flow velocity determination module 230may determine the weight of each receiving point based on the distancebetween each receiving point and the detection point. For example, thefirst flow velocity determination module 230 may take a ratio of thedistance between each receiving point and the detection point and a sumof the distances between all the receiving points and the detectionpoint as the weight of each receiving point. For example, the distancebetween the detection point D and the receiving point 1-1, the distancebetween the detection point D and the receiving point 1-2, . . . , andthe distance between the detection point D and the receiving point 16-8,may be 20 mm, 25 mm, . . . 50 mm, respectively, and a sum of thedistances may be 3840 mm; and the weight of the receiving point 1-1, thereceiving point 1-2, . . . , and the receiving point 16-8 may be20/3840=0.0052, 25/3840=0.0065, . . . , and 50/3840=0.0130,respectively.

The embodiments of the present disclosure may set the weight of eachreceiving point to be positively related to the distance between eachreceiving point and the at least one detection point, which may improvethe resolution of the image.

In some embodiments, the weight of each receiving point may benegatively correlated with the distance between each receiving point andthe at least one detection point. For example, the closer the receivingpoint is to a certain detection point, the greater the weight of thereceiving point relative to the detection point. As shown in FIG. 5 a ,the closer the receiving point 1-1, the receiving point 1-5, . . . , orthe receiving point 2-5 to the detection point, the greater the weightof the receiving point 1-1, the receiving point 1-5, . . . , or thereceiving point 2-5.

In some embodiments, the first flow velocity determination module 230may determine the weight of each receiving point based on a reciprocalvalue of the distance between each receiving point and the detectionpoint. For example, the first flow velocity determination 230 maydetermine a ratio of a reciprocal value of the distance between eachreceiving point and the detection point to a sum of the reciprocalvalues of the distances between all the receiving points and thedetection point. For example, the distance between the detection point Dand the receiving point 1-1, the distance between the detection point Dand the receiving point 1-2, . . . , and the distance between thedetection point D and the receiving point 16-8, may be 20 mm, 25 mm, . .. 50 mm, respectively, a corresponding reciprocal value of the distancemay be 0.05, 0.04, . . . , 0.02, respectively, a sum of the reciprocalvalues of the distance may be 3.2; and the weight of the receiving point1-1, the receiving point 1-2, . . . , the receiving point 16-8 may be0.05/3.2=0.015625, 0.04/3.2=0.0125, . . . , 0.02/3.2=0.00625,respectively.

The embodiments of the present disclosure may set the weight of eachreceiving point to be negatively correlated with the distance betweeneach reception point and the at least one detection point, which canreduce artifacts of the image.

In some embodiments, the first flow velocity determination module 230may determine, using the weight of each receiving point in each group ofthe array elements, a weighed sum of the spatial displacement vector ofeach receiving point in each group of the array elements to obtain theresultant spatial displacement vector corresponding to each group of thearray elements.

In some embodiments, the first flow velocity determination module 230may determine the resultant spatial displacement vector corresponding toeach group of the array elements by a formula (3):

$\begin{matrix}{p_{k} = \frac{{\sum{\omega_{k}^{m}p_{k}^{m}}},}{\sum\omega_{k}^{m}}} & (3)\end{matrix}$

Wherein p_(k) represents a resultant spatial displacement vector of thek^(th) group of array elements; ω_(k) ^(m) represent a weight of them^(th) receiving point of the k^(th) group of array elements; and p_(k)^(m) represents a spatial displacement vector of the m^(th) receivingpoint of the k^(th) group of array elements.

Further regarding the above example, the first flow velocitydetermination module 230 may determine the resultant spatialdisplacement vector p₁ corresponding to the first group of arrayelements based on the spatial displacement vectors p₁ ¹, p₁ ², . . . ,p₁ ¹⁶ and the weights ω₁ ¹, ω₁ ², . . . , ω₁ ¹⁶ of the detection point Dcorresponding to the receiving point 1-1, the receiving point 1-2, . . ., the receiving point 1-16 in the first group of array elements.Similarly, the first flow velocity determination module 230 maydetermine the resultant spatial displacement vectors p₂, p₃, . . . , p₁₆of the detection point D corresponding to the second group of arrayelements, the third group of array elements, . . . , and the 16^(th)group of array elements, respectively.

In 720, a first characteristic matrix corresponding to each group ofarray elements may be determined based on the resultant spatialdisplacement vector corresponding to each group of the array elements.

The first characteristic matrix corresponding to each group of arrayelements may be a matrix obtained based on components of the phasechange of the reflected signals corresponding to the two adjacentscanning signals received by each group of array elements on horizontaland vertical directions in a waveform diagram coordinate system of thereflected signals.

In some embodiments, the first flow velocity obtaining module 230 maydetermine components of unit phase change rate along the X-axis andZ-axis, respectively, based on the resultant spatial displacement vectorcorresponding to each group of the array elements. The X-axis and theZ-axis may be parallel to the horizontal and vertical direction of thedetection region, respectively.

Specifically, the first flow velocity obtaining module 230 may obtainthe first characteristic matrix corresponding to each group of arrayelements based on Equation (4):

$\begin{matrix}{{a = \begin{bmatrix}{\frac{\partial\phi_{k}}{\partial x} = {\frac{\omega_{0}}{c}p_{kx}^{T}}} & {\frac{\partial\phi_{k}}{\partial z} = {\frac{\omega_{0}}{c}p_{kz}^{T}}}\end{bmatrix}},} & (4)\end{matrix}$

Wherein

$\frac{\partial\phi_{k}}{\partial x}{and}\frac{\partial\phi_{k}}{\partial z}$

represent components of the unit phase change rate along the X-axis andZ-axis corresponding to the k^(th) group of array elements,respectively; ω₀ represents an angular frequency of transmission pulse;c represents a speed of the scanning signal; and p_(kx) ^(T) and p_(kz)^(T) represent components of a transposition matrix p^(T) of theresultant spatial displacement vector of the k^(th) group of arrayelements along the X-axis and Z-axis, respectively, which may bedetermined based on the location relationship among the at least onedetection point, the at least one transmission point, and the pluralityof receiving points.

In 730, the first flow velocity of the at least one detection point maybe determined based on the phase change rate of the at least onedetection point corresponding to each group of array elements and/or thefirst characteristic matrix corresponding to each group of the arrayelements.

In some embodiments, a relationship between the first flow velocity ofthe at least one detection point and the phase change rate may representby Equation (5):

$\begin{matrix}{{\overset{\bullet}{\phi} = {\frac{\omega_{0}}{c}p^{T}v}},} & (5)\end{matrix}$

Wherein {dot over (ϕ)} represents the phase change rate; v representsthe first flow velocity of the at least one detection point; and p^(T)represents the transposition matrix of the resultant spatialdisplacement vector.

In some embodiments, the first flow velocity v may be decomposed into acomponent v_(x) along the horizontal axis and a component v_(z) alongthe vertical axis, a right end of the formula (5) may be decomposed intoa product of the first matrix and the first flow velocity along thehorizontal axis is based on Equation (6):

$\begin{matrix}{{{\overset{\bullet}{\phi}}_{k} = {\begin{bmatrix}\frac{\partial\phi_{k}}{\partial x} & \frac{\partial\phi_{k}}{\partial z}\end{bmatrix}\begin{pmatrix}v_{x} \\v_{z}\end{pmatrix}}},} & (6)\end{matrix}$

In order to facilitate the calculation, let

${a = \begin{bmatrix}\frac{\partial\phi_{k}}{\partial x} & \frac{\partial\phi_{k}}{\partial z}\end{bmatrix}},{{{and}b} = {\overset{\bullet}{\phi}}_{k}},$

and the formula (6) may be simplified to Equation (7):

a _(k) v=b _(k),  (7)

In some embodiments, the first flow velocity determination module 230may determine a first auxiliary calculation matrix corresponding to eachgroup of the array elements based on the phase change rate of the atleast one detection point corresponding to each group of array elementsand/or the first characteristic matrix corresponding to each group ofthe array elements.

In some embodiments, the first auxiliary calculation matrix may be aproduct of the transposition matrix of the first characteristic matrixof each array element and the phase change rate a_(k) ^(T)b_(k).

In some embodiments, the first flow velocity determination module 230may determine a second auxiliary calculation matrix corresponding toeach group of array elements based on the first characteristic matrixcorresponding to each group of the array elements. In some embodiments,the second auxiliary calculation matrix may be a product of thetransposition matrix of the first characteristic matrix of each group ofarray elements and the first characteristic matrix a_(k) ^(T)a_(k).

In some embodiments, the first flow velocity determination module 230may obtain a third auxiliary calculation matrix by accumulating thefirst auxiliary calculation matrix corresponding to each group of arrayelements. Specifically, the third auxiliary calculation matrix may bedetermined based on Equation (8):

A ^(T) B=Σ _(k) a _(k) ^(T) b _(k),  (8)

In some embodiments, the first flow velocity determination module mayobtain a fourth auxiliary calculation matrix by accumulating the secondauxiliary calculation matrix corresponding to each group of the arrayelements. Specifically, the fourth auxiliary calculation matrix may bedetermined based on Equation (9):

A ^(T) A=Σ _(k) a _(k) ^(T) a _(k),  (9)

In some embodiments, the first flow velocity determination module 230may determine the first flow velocity of the at least one detectionpoint based on the third auxiliary calculation matrix and the fourthauxiliary calculation matrix.

In some embodiments, the first flow velocity may be determined based onEquation (10):

v=(A ^(T) A)⁻¹(A ^(T) b),  (10)

In some embodiments, the first flow velocity determination module 230may determine the first flow of the at least one detection point by theGPU parallel computing.

Specifically, the GPU may parallel calculate the phase change rate, theresultant spatial displacement vector, the first characteristic matrix,and the first auxiliary calculation matrix corresponding to each groupof array elements, etc., which can improve the computational efficiency.

FIG. 8 is a flowchart illustrating an exemplary process of determining asecond flow velocity of at least one detection point according to someembodiments of the present disclosure. In some embodiments, the process800 may be performed by the scanning device 110 and/or the processingdevice 120. For example, the process 800 may be implemented as a set ofinstructions (e.g., an application) stored in a storage device (e.g.,the storage device 150). In some embodiments, the flow velocitydetection system 100 (e.g., the processing device 120) may execute theset of instructions and may accordingly be directed to perform theprocess 800. In some embodiments, the process 800 may be accomplishedwith one or more additional operations not described and/or without oneor more of the operations discussed. Additionally, the order of theoperations of process 800 illustrated in FIG. 8 and described below isnot intended to be limiting.

In 810, a time intensity gradient and/or a spatial intensity gradient ofthe at least one detection point may be determined based on the imagedata.

An optical flow field may be a projection image of a movement field on atwo-dimensional plane. It should be understood that the movement fieldmay be used to describe the movement, and the optical field may reflectgrayscale distribution of different projection images in the projectionimage sequence, and thus the movement field of the three-dimensionalspace may be transferred to the two-dimensional plane. Therefore, theoptical flow field may correspond to the movement field in an idealstate.

The optical flow may be an instantaneous movement speed of theprojection point corresponding to the detection point on the projectionimage. In some embodiments, the optical flow may be represented by achanging trend of the grayscale value of pixels in the optical flowfield. The length and direction of the arrows in the optical flow fieldmay respectively characterize the size and direction of the optical flowat each point.

In some embodiments, the second flow velocity determination module 240may obtain the optical flow field based on the image data. Specifically,the second flow velocity determination module 240 may obtain the opticalflow filed by determining all the optical flow based on a change of thegrayscale value of all the pixels in the plurality of consecutive imageframes.

In some embodiments, the second flow velocity determination module 240may determine a time intensity gradient and/or a spatial intensitygradient of the at least one detection point based on the optical flowfield.

The time intensity gradient may be the grayscale value of pixels in theoptical flow field based on a rate of time change, which may berepresented by a partial derivative of the pixel in the projection imagewith respect to the time (t) direction.

In some embodiments, the second flow determination module 240 maydetermine the time intensity gradient of the at least one detectionpoint based on Equation (11):

$\begin{matrix}{{\check{I} = \frac{\partial I}{\partial t}},} & (11)\end{matrix}$

Wherein {hacek over (I)} represents the time intensity gradient of theat least one detection point, I represents the optical flow field, and trepresents a time interval of a plurality of optical flow field framesthat form the optical flow field.

The spatial intensity gradient may be a gradient of a grayscale value ofpixels in the optical flow field based on the position change, which maybe represented by partial derivatives of pixels in the projection imagealong the X-axes and Z-axes. In some embodiments, the second flowvelocity determination 240 may determine the spatial intensity gradientof the at least one detection point based on Equation (12):

$\begin{matrix}{{{\nabla I} = {\frac{\partial I}{\partial x} + \frac{\partial I}{\partial z}}},} & (12)\end{matrix}$

Wherein ∇I represents the spatial intensity gradient of the at least onedetection point; I represents the optical flow field; x represents aunit distance of the optical flow field along the horizontal axis; and zrepresents a unit distance of the optical flow field along the verticalaxis.

In 820, the second flow velocity of the at least one detection point maybe determined based on the time intensity gradient and/or the spatialintensity gradient of the at least one detection point.

The second flow velocity may be a flow velocity of the detection pointbased on the time intensity gradient and/or the spatial intensitygradient of pixels of the image, which may be represented by aninstantaneous speed of the optical flow.

Specifically, assuming that a pixel I(x,z,t) corresponding to thedetection point moves a distance of (dx, dz) in dt time on the twoadjacent image frames, based on the assumption that the grayscale valueof the same pixel does not change before and after the motion, a basicconstraint Equation (13) may be obtained:

I(x,z,t)=I(x+dx,z+dz,t+dt),  (13)

Further, a right side of Equation (13) may be expanded based on Taylorformula, and Equation (14) may be obtained:

$\begin{matrix}{{{I\left( {x,z,t} \right)} = {{I\left( {x,z,t} \right)} + {\frac{\partial I}{\partial x}{dx}} + {\frac{\partial I}{\partial z}{\partial z}} + {\frac{\partial I}{\partial t}{dt}} + \varepsilon}},} & (14)\end{matrix}$

Wherein ε represents a second-order infinitesimal term, which may beneglectable.

Further, the second flow velocity determination module 240 maysimultaneously subtract I(x,z,t) from both ends of Equation (14), anddivide by dt at the same time to obtain Equation (15):

$\begin{matrix}{{{{\frac{\partial I}{\partial x}\frac{dx}{dt}} + {\frac{\partial I}{\partial z}\frac{dz}{dt}} + {\frac{\partial I}{\partial t}\frac{dt}{dt}}} = 0},} & (15)\end{matrix}$

Wherein

$\frac{\partial I}{\partial x}{and}\frac{\partial I}{\partial z}$

represent a rate vector v_(x) of the second flow velocity v along theX-axis and a rate vector v_(z) of the second flow velocity v along theZ-axis, respectively;

$\frac{\partial I}{\partial x}{and}\frac{\partial I}{\partial z}$

represent components of the spatial intensity gradient ∇I along theX-axis and Z-axis, and

$\frac{\partial I}{\partial t}$

represents the time intensity gradient {hacek over (I)}.

In some embodiments, a relationship among the second flow velocity, thespatial intensity gradient, and the time intensity gradient of the atleast one detection point may be represented by Equation (16):

ΔI*v={hacek over (I)},  (16)

In some embodiments, Equation (16) may be converted into Equation (17):

$\begin{matrix}{{{\left( {\frac{\partial I}{\partial x} + {{iI}\frac{\phi}{\partial x}\frac{\partial I}{\partial z}} + {{iI}\frac{\phi}{\partial z}}} \right)\begin{pmatrix}v_{x} \\v_{z}\end{pmatrix}} = \overset{\bullet}{I}},} & (17)\end{matrix}$

Wherein i represents the i^(th) image frame;

$\frac{\partial I}{\partial x} + {{iI}\frac{\phi}{\partial x}{and}\frac{\partial I}{\partial z}} + {{iI}\frac{\phi}{\partial z}}$

represent components of position change rates of the optical flowcorresponding to the detection point of the i^(th) image frame along theX-axis and Z-axis, respectively; and İ represents a time change rate ofthe optical flow corresponding to the detection point.

In some embodiments, let

${\left( {\frac{\partial I}{\partial x} + {{iI}\frac{\phi}{\partial x}\frac{\partial I}{\partial z}} + {{iI}\frac{\phi}{\partial z}}} \right) = A},{{{and}\overset{\bullet}{I}} = b},$

and the formula (17) may be converted into Equation (18):

Mv=N,  (18)

Wherein M represents a spatial intensity gradient matrix correspondingto at least consecutive plurality of image frames; v represents thesecond flow velocity of the detection point; and N represents a spatialintensity gradient matrix corresponding to the at least consecutiveplurality of image frames.

Further, the second flow velocity determination module 240 may obtainM^(T)Mv=M^(T)N by simultaneously multiplying a transpose M^(T) of thematrix M.

In some embodiments, the second flow velocity determination module 240may perform simplification and/or calculation based on a real part ofthe data: real(M^(T)Mv)=real(M^(T)N).

Further, the second flow velocity determination module 240 may obtainthe second flow velocity based on Equation (19):

v=(M ^(T) M)⁻¹(M ^(T) N),  (19)

Wherein

${M^{T}N} = {\begin{bmatrix}{\sum_{i}\frac{\partial I^{2}}{\partial x}} & {\sum_{i}{\frac{\partial I}{\partial x}\frac{\partial I}{\partial z}}} \\{{\sum}_{i}\frac{\partial I}{\partial x}\frac{\partial I}{\partial z}} & {\sum_{i}\frac{\partial I^{2}}{\partial z}}\end{bmatrix}.}$

In the embodiments of the present disclosure, the second flow velocityof the at least one detection point may be calculated by using anoptical flow method based on the image data, and the flow velocity ofthe detection point in the three-dimensional movement field may beconverted into the two-dimensional movement field for calculation.

FIG. 9 is a flowchart illustrating an exemplary process of flow velocitycalibration according to some embodiments of the present disclosure. Insome embodiments, the process 900 may be performed by the scanningdevice 110 and/or the processing device 120. For example, the process900 may be implemented as a set of instructions (e.g., an application)stored in a storage device (e.g., the storage device 150). In someembodiments, the flow velocity detection system 100 (e.g., theprocessing device 120) may execute the set of instructions and mayaccordingly be directed to perform the process 900. In some embodiments,the process 900 may be accomplished with one or more additionaloperations not described and/or without one or more of the operationsdiscussed. Additionally, the order of the operations of process 900illustrated in FIG. 9 and described below is not intended to belimiting.

As set forth above, the first flow velocity may be a flow velocity ofthe detection point determined based on the phase change of thereflected signals of the detection point; the second flow velocity maybe a flow velocity of the detection point determined based on timechange and spatial change of pixel intensity of the image. The firstflow velocity and the second flow velocity may use the same image dataand may be obtained based on the time resolution (phase change) andspatial resolution (pixel intensity) of the system, respectively, whichcan perform mutual verification and/or calibration.

In 910, a difference between the first flow velocity and the second flowvelocity of the at least one detection point may be determined.

The difference between the first flow velocity and the second flowvelocity of the at least one detection point may represent a size of thedifference in speed and direction between the first flow velocity andthe second flow velocity of the at least one detection point.

In some embodiments, the flow velocity calibration module 250 may obtaina speed difference between the first flow velocity and the second flowvelocity base on a difference, or a difference percentage, etc., betweenthe first flow velocity and the second flow velocity of the at least onedetection point, and For example, a first flow speed of the detectionpoint Q may be 20, a second flow speed may be 22, and a differencebetween the first flow speed and the second flow speed may be 22−20=2.As another example, the first flow speed of the detection point Q may be20, the second flow speed may be 30, and a difference between the firstflow speed and the second flow speed may be (30−20)/20×100%=50%.

In some embodiments, the flow velocity calibration module 250 may obtaina difference in direction between the first flow velocity and the secondflow velocity based on a size of an included angle between the firstflow velocity and the second flow velocity of the at least one detectionpoint. For example, an included angle between the first flow velocity ofthe detection point Q and the X-axis may be 30°, an included anglebetween the second flow velocity and the X-axis, and a difference indirection between the first flow velocity and the second flow velocitymay be 40−30=10.

In some embodiments, the flow velocity calibration module 250 may obtaina difference between the first flow velocity and the second flowvelocity based on a size of a modulus of a vector difference between thefirst flow velocity and the second flow velocity of the at least onedetection point. For example, the first flow velocity of the detectionpoint Q may be {right arrow over (a)}, the second flow velocity may be{right arrow over (b)}, and the modulus of the vector difference betweenthe first flow velocity and the second flow velocity may be |{rightarrow over (c)}|=|{right arrow over (a)}−{right arrow over (b)}|.

In 920, in response to that the difference is not greater than athreshold, the target flow velocity of the at least one detection pointmay be determined based on the first flow velocity and the second flowvelocity of the at least one detection point.

The threshold may be a value for evaluating the difference between thefirst flow velocity and the second flow velocity of the at least onedetection point. In some embodiments, the threshold may be set manuallyin advance.

In some embodiments, the threshold may include a first threshold and asecond threshold. The first threshold may be a value for evaluating thedifference between the first flow speed and the second flow speed of theat least one detection point. The second threshold may be a value forevaluating the difference in the directions between the first flowvelocity and the second flow velocity of the at least one detectionpoint. Further regarding the above example, if the first threshold is 5,the second threshold is 20°, the difference in direction between thefirst flow velocity and the second flow velocity of the detection pointis 10, it may be determined that a target flow velocity of the detectionpoint Q is an average value of the first flow velocity 20 and the secondflow velocity 22 of the detection point Q is 21 and an angle thatbetween the direction and the X-axis is 35.

In some embodiments, the threshold may further include a thirdthreshold. The third threshold may be a value for evaluating thedifference in speed and direction between the first flow velocity andthe second flow velocity of the at least one detection point. Furtherregarding g the above example, if the third threshold is 6, a differencebetween a first flow velocity d and a second flow velocity {right arrowover (b)} of the detection point Q is |{right arrow over (c)}|=4, it maybe determined that a rate of the target flow velocity of the detectionpoint Q is an average of the first flow velocity and the second flowvelocity

$\frac{{❘\overset{\rightarrow}{a}❘} + {❘\overset{\rightarrow}{b}❘}}{2},$

the direction may be a direction of a resultant vector {right arrow over(a)}+{right arrow over (b)} of the first flow velocity and the secondflow velocity.

In 930, in response to that the difference is greater than thethreshold, a target flow velocity of at least one adjacent detectionpoint adjacent to the at least one detection point may be determined,and the target flow velocity of the at least one adjacent detectionpoint may be interpolated to obtain the target flow velocity of the atleast one detection point.

It should be understood that when the difference between the first flowvelocity and the second flow velocity of the at least one detectionpoint is large, there may be an error in the image data corresponding tothe at least one detection point, and the flow velocity calibrationmodule may obtain the target flow velocity based on the target flowvelocity of other adjacent detection points.

Further regarding the above example, if the first threshold is 10%, andthe difference between the first flow velocity and the second flowvelocity of the detection point D is 50%, the target flow velocity ofthe detection point D may be obtained by interpolation.

In some embodiments, the interpolation may include but is not limited toat least one of the adaptive interpolation algorithms such as a nearestneighbor interpolation, a quadratic interpolation, and a cubicinterpolation. In some embodiments, the flow velocity calibration module250 may select at least one adjacent detection point adjacent to the atleast one detection point based on the different interpolationalgorithms.

For example, the flow velocity calibration module 250 may use a targetflow velocity of the adjacent detection point closest to the detectionpoint as the target flow velocity of the detection point based on thenearest neighbor interpolation algorithm.

As another example, the flow velocity calibration module 250 may selecta nearest left detection point and a nearest right detection point ofthe detection point in a lateral direction based on the quadraticinterpolation algorithm, and a nearest upper detection point and anearest lower detection point of the detection point in a longitudinaldirection as nearby detection points of the detection point. Further, anaverage value of lateral components of a target flow velocity of thenearest left detection point and the right detection point may beobtained as a lateral target flow velocity of the detection point; anaverage value of longitudinal components of the target flow velocity ofthe nearest upper detection point and the lower detection point as alongitudinal target flow velocity of the detection point; the targetflow velocity of the detection point may be obtained based on thelateral target flow velocity of the detection point and the longitudinaltarget flow velocity of the detection point.

The beneficial effects of the embodiments of the present disclosure mayinclude but are not limited to: (1) the two-dimensional flow velocity ofeach detection point may be determined by grouping the array elementsand utilizing the location relationship among the transmission point(i.e., the transmission focus), the receiving point (i.e., the arrayelement), and/or the detection point in combination with the phasechange. Compared with a multi-angle transmission mode, the condition ofthe phase change of the reflected signals under multiple angles may beobtained by a single transmission, and the flow velocity of the targetobject perpendicular to the transmission direction may be detected,which can improve the utilization rate of the system to the data and theaccuracy of the system frame rate and speed evaluation; (2) under thefull aperture transmission mode, the imaging efficiency can be improvedand the divergent wave mode can be adopted, so that the transmissionscanning signals can point to the same focus position, which can notonly improve the signal-to-noise ratio, but also increase the frame rateof the system, thus improving the time resolution of the system; (3)based on the image data and the utilization of the optic flow method forcalculating the second flow velocity of the at least one detectionpoint, the flow velocity of the detection point in the three-dimensionalmovement field may be converted to the two-dimensional movement fieldfor calculation; (4) the first flow velocity and the second flowvelocity may be obtained based on the time resolution (phase change) andspatial resolution (pixel intensity) of the system, respectively, andthus mutual verification and/or calibration may be achieved; (5) byusing a pixel beam synthesis method, using GPU parallel computing basedon a mode of grouped array elements, computing efficiency may beimproved and hardware and time costs may be reduced. It should beunderstood that different embodiments may have different beneficialeffects, in different embodiments, the possible beneficial effects maybe any one or a combination of the above, or any other possiblebeneficial effect.

The basic concepts have been described. Obviously, for those skilled inthe art, the detailed disclosure may be only an example and may notconstitute a limitation to the present disclosure. Although notexplicitly stated here, those skilled in the art may make variousmodifications, improvements, and amendments to the present disclosure.These alterations, improvements, and modifications are intended to besuggested by this disclosure and are within the spirit and scope of theexemplary embodiments of this disclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of the specification are not necessarilyall referring to the same embodiment. In addition, some features,structures, or features in the present disclosure of one or moreembodiments may be appropriately combined.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or contexts including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, all aspects of the presentdisclosure may be performed entirely by hardware, may be performedentirely by software (including firmware, resident software, microcode,etc.), or may be performed by a combination of hardware and software.The above hardware or software may be referred to as “data block”,“module”, “engine”, “unit”, or “component”. or “system”. In addition,aspects of the present disclosure may appear as a computer productlocated in one or more computer-readable media, the product includingcomputer-readable program code.

The computer storage medium may contain a propagation data signalcontaining computer program code, for example, on baseband or as part ofa carrier wave. The propagation signal may have a variety of forms,including electromagnetic form, optical form, etc., or a suitablecombination. The computer storage medium may be any computer-readablemedium other than a computer-readable storage medium, which may beconnected to an instruction execution system, device, or device torealize communication, propagation, or transmission of a program foruse. The program code located on the computer storage medium may bepropagated through any suitable medium, including radio, cable, opticalfiber cable, RF, or the like, or any combination of the above media.

The computer program code required for the operation of each part ofthis manual can be written in any one or more program languages,including object-oriented programming languages such as Java, Scala,Smalltalk, Eiffel, jade, emerald, C++, C #, vb.net, python, etc.,conventional programming languages such as C language, visual basic,fortran2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languagessuch as python, ruby and groovy, or other programming languages. Theprogram code may run completely on the user's computer, or as a separatesoftware package on the user's computer, or partially on the user'scomputer, partially on the remote computer, or completely on the remotecomputer or processing device. In the latter case, the remote computermay be connected to the user computer through any network form, such asa local area network (LAN) or a wide area network (WAN), or connected toan external computer (such as the Internet), or in a cloud computingenvironment, or used as a service such as software as a service (SaaS).

Moreover, unless otherwise specified in the claims, the sequence of theprocessing elements and sequences of the present application, the use ofdigital letters, or other names are not used to define the order of theapplication flow and methods. Although the above disclosure discussesthrough various examples what is currently considered to be a variety ofuseful embodiments of the disclosure, it is to be understood that suchdetail is solely for that purpose and that the appended claims are notlimited to the disclosed embodiments, but, on the contrary, are intendedto cover modifications and equivalent arrangements that are within thespirit and scope of the disclosed embodiments. For example, although theimplementation of various assemblies described above may be embodied ina hardware device, it may also be implemented as a software onlysolution, e.g., an installation on an existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure and aiding in theunderstanding of one or more of the various embodiments. However, thisdisclosure may not mean that the present disclosure object requires morefeatures than the features mentioned in the claims. In fact, thefeatures of the embodiments are less than all of the features of theindividual embodiments disclosed above.

In some embodiments, the numbers expressing quantities, properties, andso forth, used to describe and claim certain embodiments of theapplication are to be understood as being modified in some instances bythe term “about,” “approximate,” or “substantially.” Unless otherwisestated, “about,” “approximate,” or “substantially” may indicate a ±20%variation of the value it describes. Accordingly, in some embodiments,the numerical parameters set forth in the description and attachedclaims are approximations that may vary depending upon the desiredproperties sought to be obtained by a particular embodiment. In someembodiments, the numerical parameters should be construed in light ofthe number of reported significant digits and by applying ordinaryrounding techniques. Although the numerical domains and parameters usedin the present application are used to confirm the range of ranges, thesettings of this type are as accurate in the feasible range in thefeasible range in the specific embodiments.

Each patent, patent application, patent application publication, andother materials cited herein, such as articles, books, instructions,publications, documents, etc., are hereby incorporated by reference inthe entirety. In addition to the application history documents that areinconsistent or conflicting with the contents of the present disclosure,the documents that may limit the widest range of the claim of thepresent disclosure (currently or later attached to this application) areexcluded from the present disclosure. It should be noted that if thedescription, definition, and/or terms used in the appended applicationof the present disclosure is inconsistent or conflicting with thecontent described in the present disclosure, the use of the description,definition and/or terms of the present disclosure shall prevail.

At last, it should be understood that the embodiments described in thedisclosure are used only to illustrate the principles of the embodimentsof this application. Other modifications may be within the scope of thepresent disclosure. Thus, by way of example, but not of limitation,alternative configurations of the embodiments of the present disclosuremay be utilized in accordance with the teachings herein. Accordingly,embodiments of the present disclosure are not limited to that preciselyas shown and described.

1. A method for flow velocity detection, comprising: obtaining imagedata; determining, based on the image data, a parameter of at least onedetection point, the parameter being related to a phase change; anddetermining a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.
 2. The methodof claim 1, wherein the obtaining image data includes: obtaining theimage data by utilizing a full aperture transmission.
 3. The method ofclaim 2, wherein the full aperture transmission includes a full aperturetransmission under an unfocused wave transmission mode.
 4. The method ofclaim 1, further comprising: grouping array elements of a scanning probeto obtain a plurality of groups of array elements, wherein each group ofarray elements of the plurality of groups of array elements includes oneor more array elements.
 5. The method of claim 4, wherein the scanningprobe includes any one of a linear array probe, a convex array probe,and a phased array probe.
 6. The method of claim 4, wherein the imagedata includes a plurality of groups of image data, each group of imagedata of the plurality of groups of image data corresponds to a group ofarray elements of the plurality of groups of array elements, and theeach group of image data is obtained by performing demodulation and beamsynthesis on reflected signals received by the corresponding group ofarray elements.
 7. The method of claim 6, the parameter related to thephase change includes a phase change rate, wherein the determining,based on the image data, a parameter of at least one detection pointincludes: determining, in the image data, at least two frames of imagedata segments that are adjacent with respect to time and received by theeach group of array elements; and determining the phase change rate ofthe at least one detection point corresponding to the each group ofarray elements based on the at least two frames of image data segmentsthat are adjacent with respect to time.
 8. The method of claim 7,wherein the determining a first flow velocity of the at least onedetection point based on the parameter related to the phase change and alocation relationship among the at least one detection point, at leastone transmission point, and a plurality of receiving points includes:calculating a characteristic matrix for each group of array elements ofthe plurality of groups of array elements, based on the parameterrelated to the phase change and the location relationship among the atleast one detection point, the at least one transmission point, and theplurality of receiving points; and integrating calculation results ofthe plurality of groups of array elements to obtain the first flowvelocity of the at least one detection point.
 9. The method of claim 7,wherein the determining a first flow velocity of the at least onedetection point based on the parameter related to the phase change and alocation relationship among the at least one detection point, at leastone transmission point, and a plurality of receiving points includes:determining a resultant spatial displacement vector corresponding to theeach group of array elements based on the location relationship amongthe at least one detection point, the at least one transmission point,and the plurality of receiving points; determining a firstcharacteristic matrix corresponding to the each group of array elementsbased on the resultant spatial displacement vector corresponding to theeach group of array elements; and determining the first flow velocity ofthe at least one detection point based on the phase change rate of theat least one detection point corresponding to the each group of arrayelements and the first characteristic matrix corresponding to the eachgroup of array elements.
 10. The method of claim 9, wherein thedetermining the first flow velocity of the at least one detection pointbased on the phase change rate of the at least one detection pointcorresponding to the each group of array elements and the firstcharacteristic matrix corresponding to the each group of array elementsincludes: determining a first auxiliary calculation matrix correspondingto the each group of array elements based on the phase change rate ofthe at least one detection point corresponding to the each group ofarray elements and the first characteristic matrix corresponding to theeach group of array elements; determining a second auxiliary calculationmatrix corresponding to the each group of array elements based on thefirst characteristic matrix corresponding to the each group of arrayelements; determining a third auxiliary calculation matrix byaccumulating the first auxiliary calculation matrix corresponding to theeach group of array elements; determining a fourth auxiliary calculationmatrix by accumulating the second auxiliary calculation matrixcorresponding to the each group of array elements; and determining thefirst flow velocity of the at least one detection point based on thethird auxiliary calculation matrix and the fourth auxiliary calculationmatrix.
 11. The method of claim 9, wherein the determining a resultantspatial displacement vector corresponding to the each group of arrayelements based on the location relationship among the at least onedetection point, the at least one transmission point, and the pluralityof receiving points includes: determining a spatial displacement vectorcorresponding to each receiving point of the plurality of receivingpoints based on a location relationship among the at least one detectionpoint, the at least one transmission point, and the each receivingpoint; and determining the resultant spatial displacement vectorcorresponding to the each group of array elements based on the spatialdisplacement vector corresponding to the each receiving point and aweight corresponding to the each receiving point.
 12. The method ofclaim 11, wherein the determining the resultant spatial displacementvector corresponding to the each group of array elements based on thespatial displacement vector corresponding to the each receiving pointand a weight corresponding to the each receiving point includes:determining, using the weight of the each receiving point in the eachgroup of array elements, a weighed sum of the spatial displacementvector of the each receiving point in the each group of array elementsto obtain the resultant spatial displacement vector corresponding to theeach group of array elements.
 13. The method of claim 11, wherein theweight corresponding to the each receiving point is determined based ona distance between the each receiving point and the at least onedetection point.
 14. The method of claim 1, further comprising:determining, based on the image data, a time intensity gradient and aspatial intensity gradient of the at least one detection point; anddetermining a second flow velocity of the at least one detection pointbased on the time intensity gradient and the spatial intensity gradientof the at least one detection point.
 15. The method of claim 14, furthercomprising: performing a velocity calibration based on the first flowvelocity and the second flow velocity of the at least one detectionpoint to obtain a target flow velocity of the at least one detectionpoint.
 16. The method of claim 15, wherein the velocity calibrationincludes: determining a difference between the first flow velocity andthe second flow velocity of the at least one detection point; inresponse to that the difference is not greater than a threshold,determining the target flow velocity of the at least one detection pointbased on the first flow velocity and the second flow velocity of the atleast one detection point; and in response to that the difference isgreater than the threshold, determining a target flow velocity of atleast one adjacent detection point adjacent to the at least onedetection point, and interpolating the target flow velocity of the atleast one adjacent detection point to obtain the target flow velocity ofthe at least one detection point.
 17. The method of claim 1, wherein theimage data includes data obtained by scanning under a mode B.
 18. Themethod of claim 1, wherein the determining a first flow velocity of theat least one detection point includes: determining the first flowvelocity of the at least one detection point by graphics processing unit(GPU) parallel computing.
 19. A system for flow velocity detection,comprising: at least one storage medium storing a set of instructions;at least one processor in communication with the at least one storagemedium, when executing the stored set of instructions, the at least oneprocessor causes the system to: obtain image data; determine, based onthe image data, a parameter of at least one detection point, theparameter being related to a phase change; and determine a first flowvelocity of the at least one detection point based on the parameterrelated to the phase change and a location relationship among the atleast one detection point, at least one transmission point, and aplurality of receiving points.
 20. (canceled)
 21. A non-transitorycomputer readable medium including executable instructions, theinstructions, when executed by at least one processor, causing the atleast one processor to effectuate a method comprising: obtaining imagedata; determining, based on the image data, a parameter of at least onedetection point, the parameter being related to a phase change; anddetermining a first flow velocity of the at least one detection pointbased on the parameter related to the phase change and a locationrelationship among the at least one detection point, at least onetransmission point, and a plurality of receiving points.